ssd capacity

I’m researching prices on sata ssd replacement drives in a couple of computers (waiting for the Memorial Day sales.) I have a question on drive capacity as it relates to the technology. Most of the brand name drives are listed (for my needs) at 500GB. Some of the store-brand drives are listed at 512GB. What is the difference? And don’t say 12GB!!!

Others are listed as 480GB and 240GB. Is there a difference in the underlying technology that accounts for the size variation? The newest, most popular, ssd are listed in the round numbers, i.e. 250GB, 500GB, 1TB. Does that mean the 512GB drives use older technology? Is there a reason to avoid the generic drives, or even the brand names, that have 512GB capacity?

MB vs. MiB
GB vs. GiB

Are you sure they all say GB? Do not some refer to GB and others to GiB?

Please read the fine print in the manufacturer spec sheet, there should be an explanation of what they mean by “GB”.
Then consider that SSDs have some spare capacity reserved for wear-out balance or bad cell replacement and we simply don’t know (in general) how much spare space they have reserved beyond advertised capacity; so I think that inferring technology or raw capacity from advertised capacity alone is useless.


As best I can tell, all disk drive sellers try to make their drives look bigger than they actually are.

Given the current market situation, I wouldn’t wait – it looks as if everything containing semi-conductors will increase in price …
[HR][/HR]GiB or GB – TiB or TB –

  • Without an “i” it’s a marketing capacity …
  • For capacities less than or equal to 512 GB, usually a power of 2 was advertised – 512 MB, 1024 MB, 2 GB, 4 GB, 8 GB, 16 GB, 32 GB, 64 GB, 128 GB, 256 GB, 512 GB …
  • With terabyte, it’s simply 1 TB, 2 TB, 3 TB …

Whichever drive you purchase, Linux will report less than what the label indicates – for example, 128 GB, 1 TB, 4 TB and, 500 GB drives –

 # inxi --disk
Drives:    Local Storage: total: 5.11 TiB
           ID-1: /dev/sda vendor: Intenso model: SSD Sata III size: 111.79 GiB 
           ID-2: /dev/sdb vendor: Western Digital model: WD10EZEX-60M2NA0 size: 931.51 GiB 
           ID-3: /dev/sdc vendor: Western Digital model: WD40EZRZ-22GXCB0 size: 3.64 TiB 
           ID-4: /dev/sdd vendor: Seagate model: ST3500418AS size: 465.76 GiB 

A popular model: 500GB Crucial MX500 2.5" (6.4cm) SATA 6Gb/s 3D-NAND TLC (CT500MX500SSD1). I bought the 250GB model last year.

I’ve been choosing to buy only SSDs sized to powers of 2, so only 128, 256 or 512, except for a couple of 120 from before adopting the policy.

Thanks to all for the answers. @karlmistelberger mentioned 3D-Nand TLC. That touched on what I thought. Perhaps, the size designation might have been related to the chip architecture or something and one designation meant a superior product. Now I see as @nrickert said: “it’s marketing.”

I also have a BX drive:

erlangen:~ # inxi -D 
Drives:    Local Storage:total: 6.38 TiB used: 3.14 TiB (49.2%)  
           ID-1: /dev/nvme0n1 vendor: Samsung model: SSD 950 PRO 512GB size: 476.94 GiB  
**           ID-2: /dev/sda vendor: Crucial model: CT2000BX500SSD1 size: 1.82 TiB  **
           ID-3: /dev/sdb vendor: Western Digital model: WD40EZRX-22SPEB0 size: 3.64 TiB  
           ID-4: /dev/sdc vendor: Samsung model: SSD 850 EVO 500GB size: 465.76 GiB  
erlangen:~ #

No one has mentioned the Hynix drives from Hyundai. The specs and performance are essentially equal to Samsung for about 10% lower cost. Samsung’s advantage seems to be the included software for cloning and monitoring.

Reported volume in MB/GB/TB depends on a used chips + reserved space + number of cell levels (1, 2, 3, 4).
Often 480 and 512 MB are MLC = 2 level cells (but Samsung tells 3 level cells are MLC), and 500 MB are TLC = 3 level cells.

Samsung drives was faster and reliable (but not all of them - troubles with 850 and 860).

Check the list here for devices…